st: Determining mutual exclusivity for a series of dummy variables.

[Stephen Cranney <scranney@sas.upenn.edu>]

Hi all, quick question. I have about twenty separate dummy variables
that, in theory, are supposed to be mutually exclusive. I did a
regression with all the variables and it didn't kick out one of the
variables automatically, so I assume that there is either some overlap
or there are cases with zero values for all the variables. I checked
the cases used in the regression using the "estimates store sample"
command, and none of them have zero values for all the dummy
variables, which leads me to believe that they aren't mutually
exclusive. I've checked my coding numerous times and the coding for
the variables seems accurate.
So my question is: is there a parsimonious way to quickly check
whether the series of dummy variables are mutually exclusive without
having to check every combination by hand?

Thanks in advance,

Stephen
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/